Method of pneumatically controlling a thread or a thread bundle guided at right angles with respect to at least one airstream and apparatus for implementing the method

ABSTRACT

A method of and apparatus for pneumatically controlling a thread or a thread bundle guided at right angles with respect to at least one airstream and of detecting changes of the air-stream caused by changes in the thread thickness or by the absence of the thread, wherein the thread is guided through air-streams opposed to each other, the pressure ratios of which change corresponding to the thread thickness and in that these pressure changes are detected and corresponding signals are generated.

United States Patent [191 Reufer et al.

[ Nov. 26, 1974 METHOD OF PNEUMATICALLY CONTROLLING A THREAD OR A THREAD BUNDLE GUIDED AT RIGHT ANGLES WITH RESPECT TO AT LEAST ONE AIRSTREAM AND APPARATUS FOR IMPLEMENTING THE METHOD [75] Inventors: Christian Reufer, Luzern; Dieter Guldentels, Muttenz, both of Switzerland [73] Assignees: Rieter Machine Works Ltd.,

Winterthur; Societe de la Viscose Suisse, Emmenbrucke, both of, Switzerland [22] Filed: May 3, 1973 [21] Appl. No.: 356,900

[30] Foreign Application Priority Data May 19, 1972 Switzerland 7450/72 [52] US. Cl. 73/37.7, 73/160 [51] Int. Cl. GOlb 13/08 [58] Field of Search 73/37, 37.5, 37.6, 37.7, 73/160 [56] References Cited UNITED STATES PATENTS 3,377,842 4/1968 Pitney 73/37 3,485,095 12/1969 Hirata et al 73/377 X Primary Examiner-Jerry W. Myracle Assistant Examiner-J0seph W. Roskos [5 7] ABSTRACT A method of and apparatus for pneumatically controlling a thread or a thread bundle guided at right angles with respect to at least one airstream and of detecting changes of the air-stream caused by changes in the thread thickness or by the absence of the thread, wherein the thread is guided through air-streams 0pposed to each other, the pressure ratios of which change corresponding to the thread thickness and in that these pressure changes are detected and corresponding signals are generated.

7 Claims, 6 Drawing Figures PATENTEL, FIUVZBIQM 3 25 SHEET 10F 2 METHOD OF PNEUMATICALLY CONTROLLING A THREAD OR A THREAD BUNDLE GUIDED AT RIGHT ANGLES WITH RESPECT TO AT LEAST ONE AIRSTREAM AND APPARATUS FOR IMPLEMENTING THE METHOD The present invention concerns a method of pneumatically controlling a thread or a thread bundle guided at right angles with respect to at least one airstream and of detecting changes of the airstream caused by changes caused in the thread thickness or by absence of the thread, and an apparatus for implementing the method by means of blowing nozzles connected to a source of compressed air and with means for guiding the thread, or the thread bundle respectively, at right angles with respect to the blowing nozzles.

Devices are already known for pneumatically controlling the thread thickness of a running thread in which at the end of one duct branch of a so-called pneumatic bridge arrangement a throttle guiding and measuring the thread is provided, and in which at the end of the other duct branch an adjustable throttle valve is provided as pressure compensation for said measuring throttle. A temperature sensor, arranged in a connecting duct provided between said duct branches of the pneumatic bridge arrangement, is activated by by the airstreams in this connecting duct caused by variations of the thread thickness and transmits corresponding electrical signals to a thread thickness display device. The adjustable throttle is pre-set in such manner that the air pressures in the two branch ducts are balanced at an average thread thickness.

It is a disadvantage of such devices used as thread control, e.g., for detecting a thread break that they are complex and relatively expensive.

Also known are methods and devices for improving the uniformity of textile threads and other threadlike structures in which a bundled airstream directed towards a thread is separated and subsequently its residual' intensity is measured, the value measured being transformed using means known as such in a control device into a correcting signal which in turn via a correcting element is transformed into an influence adapting the thread fineness.

The disadvantage of such arrangements is seen in that the means measuring the residual intensity of the airstream are easily contaminated by fine fibre particles carried on by the airstream.

Additionally, there is known to the art an apparatus for monitoring a yarn which is guided at a high speed, wherein the yarn to be monitored is guided between an air current of higher intensity and an air current of lower intensity. Both of the air currents are directed towards one another by means of appropriately arranged nozzles and the different intensities are produced by different air pressures. At one or both nozzles there is provided in front of the nozzle mouth a branched-off pipe or tube which is coupled with a pressure amplifier or signal transmitter. A diaphragm mounted in the same nozzle and in front of the branched-off portion serves to a certain extent as a dam-up element. The yarn is essentially guided at the same spacing from both nozzles. The distance between the yarn and the nozzles and the nozzle-air relationships are designed in such a way that for monitoring the yarn the air current generated by the high velocity yarn must be taken into account to obtain a useful control result for the yarn.

Thus there is present a drawback of such apparatus, namely, oppositely directed air currents alone are not sufficient to obtain a pressure signal which can be evaluated, i.e., the measuring technique can only be employed for yarns which are moving at high speeds.

It thus is the goal of the present invention to eliminate these disadvantages by means of a method of pneumatically controlling a thread or a thread bundle guided at right angles with respect to at least one airstream and of detecting changes of the airstream caused by changes in the thread thickness or by absence of the thread, characterized in that the thread is guided through airstreams opposed to each other the pressure ratios of which change corresponding to the thread thickness and in that these pressure changes are detected and corresponding signals are generated. The apparatus for implementing the method using blowing nozzles connected to a source of compressed air and means for guiding the thread, or the thread bundle respectively, at right angles with respect to the blowing nozzles is characterized in that at least two blowing nozzles are arranged opposed to each other the thread being guided between said nozzles and that between the source of compressed air and the blowing nozzle means are provided which can detect variations in air pressure caused by changes in the thread thickness and can transmit corresponding signals.

The invention is described in more detail in the following with reference to illustrated design examples. It is shown in:

FIG. 1 a cross-section of a nozzle body,

FIG. 2 a longitudinal section of the nozzle body according to FIG. 1 along the lines I-l FIG. 3 a cross-section of the nozzle body along the lines llII of FIG. 2 the compressed air supply duct system being indicated schematically,

FIGS. 4 through 6 a schematical view each of further design examples.

In FIG. 1 a thread 1 (monofil or multifil filament) is shown, and a cross-section of a nozzle body in which at the top and at the bottom a thread. guide 3a and 3b each is arranged, slotted and open towards the outside. These thread guides are provided for keeping the thread in a determined thread path. Furthermore, a blowing nozzle 5 in a compressed air duct 6 and a blowing nozzle 7 in a compressed air duct 8 are provided.

The distances M and N respectively (FIG. 2) between the thread guides 4a and 4b respectively and the nozzles are to be chosen as small as possible if the thread is to be guided properly. The compressed air supply system shown in FIG. 3 consists of a connection 9 to a source of compressed air (not shown), of an adjustable throttle valve 10 in a connecting duct 11 between the connection 9 and the duct 6, and of an adjustable throttle valve 12 in a connecting duct 13 between the connection 9 and the duct 8. A pressure amplifier 14 is arranged in the circuit between the throttle valve 12 and the nozzle 7. The nozzle 5 contains a bore 15 of a diameter D 15. The nozzle 7 contains a bore 16 of a diameter D 16, the diameter D 15 being chosen smaller than D 16. The diameter ratio D 15/D 16 can be, e.g., twothirds. The positions of the nozzles 5 and 7 with respect to the thread 1 preferably are chosen such that the blowing nozzle 5 extends to closer vicinity of the thread 1 (distance x) than the blowing nozzle 7 (distance y). The ratio of the distances x/y can be, e.g., one-third. Insertion of the thread 1 into the thread guides 3a, b and 4a, b can be effected by detaching the two thread guides 40 and 4b, inserting the thread into the thread guides 3a and 3b and reinserting the thread guides 40 and 4b.

The apparatus is not restricted to the type of thread guides shown; any type or combination of thread guides suitable for maintaining the thread between the nozzles is feasible.

For operation the throttle valves and 12 of the thread control device are adjusted in such manner that in the duct 6 a higher pressure p6 prevails than a pressure 28 in the duct 8. The ratio of pressures p6/p8 can be, e.g., l'O/l, i.e., if in the duct 6 a pressure p6 of, e.g., 0.4 atmospheres above atmospheric pressure prevails, a pressure 28 of 0.04 atmospheres above atmospheric pressure should prevail in the duct 8. The relations concerning the nozzle diameters D and D16, the distances x and y as well as the pressure ratios p6 and p8 are to be mutually coordinated in such manner that on one hand the air outflow from both nozzles is ensured while a thread is passing through, and that on the other hand, in the absence of the thread, e.g., due to a thread break, the air emerging from the nozzle 5 with higher energy retains the outflow of air from the nozzle 7 to such an extent, that the pressure between the nozzle 7 and the throttle valve 12 thus increases and activates the amplifier to generate a signal. The amplifier 14 in this arrangement can be used, e.g., for activating a thread cutting device. The thickness and the throughput speed of the thread can be chosen in practically any range desired.

In FIG. 4 a simpler alternative arrangement of blowing nozzles opposed to each other is shown in which a nozzle 17 and a nozzle 18 each contain a bore of the same diameter. The nozzle 17 is connected via a connecting duct 19 with the connection point 9, and the nozzle 18 is connected via a connecting duct 20 with the connection point 9. The thread 1 is guided by the thread guides (not shown) as close as possible to the nozzle 17. In operation the thread 1 partially blocks the air flowing out of the nozzle 17 and thus generates a certain pressure in the connecting duct 19. In the absence of thread 1 the amplifier l4 detects the smaller pressure thus generated in the connecting duct 19 and correspondingly transmits a signal.

In FIG. 5 a further simpler alternative arrangement is shown, comprising a nozzle 21 connected via a connecting duct 22 with the connecting point 9 and a nozzle 23 connected via a connecting duct 24 with the connecting point 9. Both nozzles 21 and 23 contain bores of the same diameter. Both nozzles extend into close vicinity of the thread 1. The amplifier 14 is arranged on a connection duct 25 connecting the two connecting ducts 22 and 24.

The thread guides (not shown) maintain the thread positioned in front of the outflow openings of the nozzles 21 and 23.

In operation the amplifier 14 in the absence of thread 1 detects the pressure changes in the connecting ducts 22, 24 and 25 and correspondingly transmits a signal.

In FIG. 6 a third alternative arrangement is shown with a nozzle each 26, 27, 28 and 29. The nozzles 26 and 27 are connected to a connecting duct 30 which establishes the connection with the connecting point 9, whereas the nozzles 28 and 29 are connected via a connecting duct 31 with the connecting point 9. The amplifier 14 is connected with the connecting ducts 30 and 31 by means of a connecting duct 32. The thread guides (not shown) keep the thread 1 guided through the intersection point of the connecting lines of the nozzles 26, 27, 28 and 29. In operation the amplifier l4 detects, if the thread 1 is absent, the changes of pressure in the connecting ducts 30, 31 and 32 and correspondingly transmits a signal.

The advantages of the described method and of the apparatus for implementing the method are:

1. very simple design which thus is economical to manufacture,

2. no moving or protruding parts on which the thread or fibrils of a thread could get caught,

3. no danger of clogging or contamination of the noz- .zles,

4. minimum maintenance work,

5. practically no forces acting on the thread and thus quality impairments restricted to a minimum.

We claim:

1. Method of pneumatically controlling a thread or a thread bundle through two airstreams directed in front of and opposite to each other comprising the steps of: guiding the thread at right angles to the two airstreams; detecting changes of one of the airstreams caused by changes in the thread thickness or by the absence of the thread; maintaining the airstreams of different intensities and guiding the thread nearer to the air-stream of higher intensity whereby the pressure changes of the airstream of smaller intensity are detected and corresponding signals are generated.

2. Method according to claim 1, wherein the airstreams of different intensity are generated by throttling at least one airstream.

3. Apparatus for pneumatically controlling a thread or thread bundle guided at right angles with respect to two airstreams comprising: two blowing nozzles arranged to oppose each other, a source of compressed air operatively connected to the nozzles, means for guiding the thread, or the thread bundle respectively, at right angles with respect to the blowing nozzles, the two blowing nozzles having different nozzle diameters, means for varying the air pressure in the nozzles, means between the means for varying the air pressure and the nozzle with the larger diameter for detecting variations in air pressure caused by changes in the thread thickness and for transmitting corresponding signals.

4. Apparatus according to claim 3, wherein the means for detecting the variations in air pressure includes a pressure amplifier.

5. Apparatus according to claim 4, wherein the pressure amplifier transmits pneumatic signals.

6. Apparatus according to claim 4, wherein the pressure amplifier transmits electrical signals.

7. Apparatus according to claim 3, wherein the means for varying the air pressure comprises a throttle valve. 

1. Method of pneumatically controlling a thread or a thread bundle through two airstreams directed in front of and opposite to each other comprising the steps of: guiding the thread at right angles to the two airstreams; detecting changes of one of the airstreams caused by changes in the thread thickness or by the absence of the thread; maintaining the airstreams of different intensities and guiding the thread nearer to the airstream of higher intensity whereby the pressure changes of the airstream of smaller intensity are detected and corresponding signals are generated.
 2. Method according to claim 1, wherein the airstreams of different intensity are generated by throttling at least one airstream.
 3. Apparatus for pneumatically controlling a thread or thread bundle guided at right angles with respect to two airstreams comprising: two blowing nozzles arranged to oppose each other, a source of compressed air operatively connected to the nozzles, means for guiding the thread, or the thread bundle respectively, at right angles with respect to the blowing nozzles, the two blowing nozzles having different nozzle diameters, means for varying the air pressure in the nozzles, means between the means for varying the air pressure and the nozzle with the larger diameter for detecting variations in air pressure caused by changes in the thread thickness and for transmitting corresponding signals.
 4. Apparatus according to claim 3, wherein the means for detecting the variations in air pressure includes a pressure amplifier.
 5. Apparatus according to claim 4, wherein the pressure amplifier transmits pneumatic signals.
 6. Apparatus according to claim 4, wherein the pressure amplifier transmits electrical signals.
 7. Apparatus according to claim 3, wherein the means for varying the air pressure comprises a throttle valve. 